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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/* $Rev$ $Date$ */
#ifndef tuscany_rss_hpp
#define tuscany_rss_hpp
/**
* RSS data conversion functions.
*/
#include "string.hpp"
#include "list.hpp"
#include "value.hpp"
#include "monad.hpp"
#include "xml.hpp"
namespace tuscany {
namespace rss {
/**
* Tags used to tag feed and entry elements.
*/
const value feed("feed");
const value entry("entry");
/**
* Convert a list of elements to a list of element values representing an RSS entry.
*/
const list<value> entryElementValues(const list<value>& e) {
const list<value> lt = filter<value>(selector(mklist<value>(element, "title")), e);
const value t = isNil(lt)? value(emptyString) : elementValue(car(lt));
const list<value> li = filter<value>(selector(mklist<value>(element, "link")), e);
const value i = isNil(li)? value(emptyString) : elementValue(car(li));
const list<value> ld = filter<value>(selector(mklist<value>(element, "description")), e);
return append<value>(list<value>() + element + entry
+ value(list<value>() + element + value("title") + t)
+ value(list<value>() + element + value("id") + i),
isNil(ld)? list<value>() : mklist<value>(value(list<value>() + element + value("content") + elementValue(car(ld)))));
}
/**
* Convert a list of elements to a list of element values representing ATOM entries.
*/
const list<value> entriesElementValues(const list<value>& e) {
if (isNil(e))
return e;
return cons<value>(entryElementValues(car(e)), entriesElementValues(cdr(e)));
}
/**
* Return true if a list of strings contains an RSS feed.
*/
const bool isRSSFeed(const list<string>& ls) {
if (!isXML(ls))
return false;
return contains(car(ls), "<rss");
}
/**
* Convert a list of strings to a list of values representing an RSS entry.
*/
const failable<list<value> > readRSSEntry(const list<string>& ilist) {
const list<value> e = readXML(ilist);
if (isNil(e))
return mkfailure<list<value> >("Empty entry");
return mklist<value>(entryElementValues(car(e)));
}
/**
* Convert a list of strings to a list of values representing an RSS feed.
*/
const failable<list<value> > readRSSFeed(const list<string>& ilist) {
const list<value> f = readXML(ilist);
if (isNil(f))
return mkfailure<list<value> >("Empty feed");
const list<value> c = filter<value>(selector(mklist<value>(element, "channel")), car(f));
const list<value> t = filter<value>(selector(mklist<value>(element, "title")), car(c));
const list<value> i = filter<value>(selector(mklist<value>(element, "link")), car(c));
const list<value> e = filter<value>(selector(mklist<value>(element, "item")), car(c));
return mklist<value>(append<value>(list<value>() + element + feed
+ value(list<value>() + element + value("title") + elementValue(car(t)))
+ value(list<value>() + element + value("id") + elementValue(car(i))),
entriesElementValues(e)));
}
/**
* Convert a list of element values representing an RSS entry to a list of elements.
*/
const list<value> entryElement(const list<value>& l) {
const value title = elementValue(elementChild("title", l));
const value id = elementValue(elementChild("id", l));
const value content = elementChild("content", l);
const bool text = isNil(content)? false : elementHasValue(content);
return append<value>(list<value>()
+ element + "item"
+ (list<value>() + element + "title" + title)
+ (list<value>() + element + "link" + id),
isNil(content)?
list<value>() :
mklist<value>(append<value>(list<value>() + element + "description",
text? mklist<value>(elementValue(content)) : elementChildren(content))));
}
/**
* Convert a list of values representing RSS entries to a list of elements.
*/
const list<value> entriesElements(const list<value>& l) {
if (isNil(l))
return l;
return cons<value>(entryElement(car(l)), entriesElements(cdr(l)));
}
/**
* Convert a list of values representing an RSS entry to an RSS entry.
* The first two values in the list are the entry id and title.
*/
template<typename R> const failable<R> writeRSSEntry(const lambda<R(const string&, const R)>& reduce, const R& initial, const list<value>& ll) {
const list<value> l = isNil(ll)? ll : (list<value>)car(ll);
return writeXML<R>(reduce, initial, mklist<value>(entryElement(l)));
}
const failable<list<string> > writeRSSEntry(const list<value>& l) {
const failable<list<string> > ls = writeRSSEntry<list<string> >(rcons<string>, list<string>(), l);
if (!hasContent(ls))
return ls;
return reverse(list<string>(content(ls)));
}
/**
* Convert a list of values representing an RSS feed to an RSS feed.
* The first two values in the list are the feed id and title.
*/
template<typename R> const failable<R> writeRSSFeed(const lambda<R(const string&, const R)>& reduce, const R& initial, const list<value>& ll) {
const list<value> l = isNil(ll)? ll : (list<value>)car(ll);
const list<value> lt = filter<value>(selector(mklist<value>(element, "title")), l);
const value t = isNil(lt)? value(emptyString) : elementValue(car(lt));
const list<value> li = filter<value>(selector(mklist<value>(element, "id")), l);
const value i = isNil(li)? value(emptyString) : elementValue(car(li));
const list<value> c = list<value>()
+ (list<value>() + element + "title" + t)
+ (list<value>() + element + "link" + i)
+ (list<value>() + element + "description" + t);
// Write RSS entries
const list<value> le = filter<value>(selector(mklist<value>(element, entry)), l);
if (isNil(le)) {
const list<value> fe = list<value>()
+ element + "rss" + (list<value>() + attribute + "version" + "2.0")
+ append(list<value>() + element + "channel", c);
return writeXML<R>(reduce, initial, mklist<value>(fe));
}
// Write a single RSS entry element with a list of values
if (!isNil(le) && !isNil(car(le)) && isList(car<value>(caddr<value>(car(le))))) {
const list<value> ce = append(c, entriesElements(caddr<value>(car(le))));
const list<value> fe = list<value>()
+ element + "rss" + (list<value>() + attribute + "version" + "2.0")
+ append(list<value>() + element + "channel", ce);
return writeXML<R>(reduce, initial, mklist<value>(fe));
}
// Write separate RSS entry elements
const list<value> ce = append(c, entriesElements(le));
const list<value> fe = list<value>()
+ element + "rss" + (list<value>() + attribute + "version" + "2.0")
+ append(list<value>() + element + "channel", ce);
return writeXML<R>(reduce, initial, mklist<value>(fe));
}
/**
* Convert a list of values representing an RSS feed to a list of strings.
* The first two values in the list are the feed id and title.
*/
const failable<list<string> > writeRSSFeed(const list<value>& l) {
const failable<list<string> > ls = writeRSSFeed<list<string>>(rcons<string>, list<string>(), l);
if (!hasContent(ls))
return ls;
return reverse(list<string>(content(ls)));
}
}
}
#endif /* tuscany_rss_hpp */
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